Method for processing and trimming a product

ABSTRACT

The present invention comprises a method for processing and trimming products such as fish fillets where the product is form frozen forming a thin frozen shell round the product and the subsequent processing of the product uses that condition to remove the fish skin and bones with more efficiency than any prior art methods whereas the quality of the product is increased due to less loss and less loss in liquid from the product than known by prior art methods.

This application claims priority to IS patent applications no. 6490,dated Aug. 6, 2002 and no 6510, dated Aug. 16, 2002.

FIELD OF THE INVENTION

The present invention relates to a method and an apparatus forprocessing and trimming products such as fish fillets.

BACKGROUND

In the last years there has been constant development in the processingof raw material for food processing such as fish products. The emphasishas been on better exploitation and quality of products as well asdemands towards increased efficiency of the processing.

Prior and present technology used in processing and in removing the fishskin damage the product when the skin is removed and the product istreated.

Methods, equipments and instruments for removing fish bones in fishfillets have been developed in the last years, and efforts have beenmade to analyse, locate and remove fish bones with methods based onadvanced computer equipment for locating and analysing fish bones.Consequently, bone removal has been attempted with advanced computerequipment.

This technology is disadvantageous because it is very expensive andunreliable in bringing appropriate results.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a method forprocessing products, such as fish fillets, which increases theefficiency, quality and value of the products. A further object of thepresent invention is making the processing of products moreadvantageous, and solving problems in processing products in a simplerand more advantageous way.

Processing products such as fish fillets is mostly focused on removingthe fish skin and bones, as well as barbs, parasites and other defects.Further processing may involve cutting the fillet into smaller pieces,depending on the nature of the final product.

In processing fish fillets, it is important to avoid unnecessaryhandling of the product, which causes looseness in the product andtherefore lowers the quality and value of the product. This will lead toreduces the possibilities for further processing of the product and theend product will be of less value.

Also, it is important to obtain high efficiency in the processing of theproduct in order to keep the waste to a minimum, thus increasing thevalue of the product.

These objectives can be reached with a processing method described herebelow.

Form Freezing

By form freezing the fish skin and the outmost layer of a product suchas a fish fillet, it is possible to treat the product without damagingthe fillet with mistreatment and looseness in the fish-meat.

By form freezing a product the outmost layer of the product is fastfrozen, so that the freezing does not extend to the core of the productbut the form of the product obtains stiffness and thereby preventreduction of the quality of the fish-meat as with traditional freezing.

When the product reaches such low temperature and the temperature of theoutmost layer is down to −30° Celsius the ice crystals in the productbecome so small that a decrease in the quality due to the freezing inthe outmost layer is negligible.

This may be performed in a freezer with a combined blow- and atouch-freezing (conduction/convection), as in an example in amulti-freezer with form freezing belt made of plurality of aluminiumdrops, but such freezers can freeze a product that much that theserequirements are fulfilled.

This way a thin freezing layer may be formed around a fish filletwithout freezing the fish-meat significantly.

Removing the Fish Skin

The main object of the present invention, which differs form prior artmethods in that as the skin of the fish is removed, it is done when thefillet is form frozen, e.g. from below and with this method the skin isremoved without fish-meat being cut simultaneously from the fillet as iscommon in known methods, where knives are used to remove the fish-meatfrom the fish skin and simultaneously take a part of the fish-meat.

Simultaneously removing the fish skin from the fish fillet, so that nofish meat is removed therewith, the look of the fillet is better, andthe quality higher than in prior methods. Also the efficiency of theprocessing is increased where a larger part of the products stays in thefillet compared to prior art methods.

Current methods for removing fish skin are rough on the fish meat andlooseness in the fillets is very often the result when fish skin isremoved using these methods. Looseness in fish fillets increases risk ofdamage of the products and decreases their value considerably. Using themethod described herein, the fish skin removal is performed on a formfreezed fillet and during the skin removal the fillet is not bent in anyway preventing loss of product quality usually obtained using currentmethods.

Bone Removing

When the bones in the fish fillets are removed with prior art methods, apart of the meat around the bones is removed, and therefore a part ofthe product is lost and becomes a waste, which often is used for a lowprice product. This additional product is relatively a large part inconventional processing of fish fillets.

The method described here, differs greatly from prior art methods inthat when the bones are removed, they are pulled out from the formfrozen fillet from the fish skin side of the fillet, where the bones arepartly frozen to the fish skin on the end facing the fish skin.

The part of the bones facing the skin have a tiny knuckle, which may becompared to pin head on the ends, and through the form freezing asdescribed earlier, the fish skin alone freezes, but not the fish-meat inthe middle.

When the bone ends freeze to the fish skin, but the fish fillet is notfrozen in the middle the bones are loose within the fish-meat but frozento the fish skin and thereby are pulled out simultaneously when the fishskin is removed.

Consequently, it is not necessary to cut fish-meat from the fish filletwhen the bones are removed and thereby the efficiency in the processingis increased.

When the bones have been removed in this way the part of the fishfillet, which with prior art methods has been removed, is still there inthe fish fillet. Thereby, the fish fillet may be cut into valuableproducts in the area, where the bones are to be found.

The part of the bones that have not been removed this way, which issmall, is subsequently removed by applying a tool, similar to pliers, sothat the part of the fish fillet that faces the fish skin and whichcontains bones is clamped and the bones are pulled out.

Other methods are possible for removing the fish bones such as equipmentthat uses rollers, combs and clamps or mechanical devices removing fishskin and bones automatically (see later).

The fillets in which the bones have not been perfectly removed, areapproximately 10% and special equipments available on the market, suchas bone scanner, may be used for analysing these fillets andsubsequently with automatic equipment, or manually removing those aside,and removing the remaining bones.

Lowered Temperature

The present invention, differs from prior art methods in that by formfreezing the fish fillet, the temperature of the product is lower duringthe processing process than in prior art methods, and thereby preventinginfluences from heat lowering the quality of the product. Thereby, thequality of the product is increased significantly compared to othermethods.

Less Looseness

Secondly, the present invention differs from prior art methods in thatwhere the product has the stiffness from the form freezing, it is easierto cut it into desirable sizes and it is possible to cut the larger partof the product in the most valuable products without any loss andthereby increasing the efficiency of the product. This part is importantin comparison to prior art methods where the loss due to the processingprevents the product from being cut into desirable sizes.

Less Liquid Loss

The present invention, also differs from prior art methods in that byform freezing the fillet, a loss in the liquid from the product isprevented where the natural liquid of the fillet is pressed out in priorart methods.

It is important to control the form freezing so that the product doesnot freeze too much or too little, where too little form freezing causesproblems in removing the fish skin and the bones, and too much formfreezing results in that it is difficult to remove the bones with themethod described here earlier. It is best that the form freezing is suchthat it extends close to 1-2 mm within the fish-meat on the fish-skinside.

DETAILED DESCRIPTION

Following is a detailed description of the present invention, wheredifferent aspects and tools are described in more detail.

In a first aspect of the present invention, a method is disclosed forprocessing fish or fish fillets with the aim of increasing the qualityand value in the processing. This is accomplished by removing the fishskin and removing at least a part of the bone area, wherein the methodcomprises:

-   -   form freezing the fish to be processed so that the necessary        form freezing for the processing is obtained, and    -   removing the fish skin after the necessary form freezing is        obtained,        wherein the form freezing has the function that the adhesion in        the fish-meat adjacent to the fish skin is larger than the        adhesion between the fish-meat and the fish skin, which follows        in that by removing the fish skin no fish-meat is removed with        the fish skin, and wherein the form freezing has also the        function that the part of the bone area that is fastened to the        fish skin is removed as the fish skin is removed.

In the present context the remaining parts of the bone area may beremoved manually.

In the present context, the form freezing comprises fast freezing theoutmost layer of the product, so that the freezing is not extendedtowards the core of the fish or the fish fillet. This may be regulatedby adjusting the speed of the form freezing such that it freezes 1-2 mmof the outmost layer of the fish. This may result in that thetemperature of the outmost layer is below −20° C., while the coretemperature of the fish-meat is higher than 0° C.

In the present context the lowering of temperature of the fish fillet inthe processing increases the value of the end product by decreasingdamages due to temperature, such as micro organism growth and chemicalchanges, as a result of changes in enzyme activity. The form freezing ofa fish fillet also causes a lowering in the temperature duringprocessing and further increases the value of the product due to lesshandling during the processing, such as looseness in the fish fillet.Furthermore, the form freezing increases the possibilities of cuttingthe product into valuable products depending on the demands for the endproduct. Even further, the form freezing of the fish fillet results inless liquid loss in the product during the handling and the processing.

In a second aspect of the present invention, an apparatus for processingfish is provided with the aim of increasing the quality of theprocessing, wherein the apparatus comprises:

-   -   cooling means for form freezing the fish,    -   device for processing the fish, and    -   device for removing skin and pin bones

The third aspect of the present invention relates to a product processedwith a method and apparatus according to any of the preceding claims.

FIGURES

Further details of the invention are disclosed in the following figures.

FIG. 1 shows a fish fillet, where bones and fish skin have not beenremoved.

FIG. 2 shows a fish fillet, which has been subjected to one way ofpreferred cutting.

FIG. 3 shows a form freezing

FIG. 4 shows a roller device

FIG. 5 shows a comb device

FIG. 6 shows a fish fillet after skin and bone removal using skinfreezing.

FIG. 7 shows a fish fillet, which has been subjected to a second way ofpreferred cutting.

FIGS. 8 to 14 show a device, which automatically removes skin and bonesfrom a fish fillet.

The numbers in the text relate to numbered items in the figures.

FIG. 1 shows a fish fillet where the bones have not been removed.

FIG. 2 shows a fish fillet 8 where the fish bones have been removed witha prior art method and a fish fillet 9 where the bones have been removedwith the new method. When fillet is cleaned with prior art method, aportion 15 is removed from the fillet, but that has large influence onhow the fillet should be cut into products. When the portion 15 isremoved, it is usually necessary to cut it into pieces numbered 10-14 inFIG. 2 and thereby the thin piece 11 is as an example not well used andthe piece 12 is difficult to use as a high value product among theproducts 10, 13 and 14. It is even difficult to obtain a good middlepiece 13 if the cut due to the fish bones is extended too far towardsthe fish fillet. This segmentation of the fillet has large influence onthe advantageousness of the processing.

When the bones are removed from a fish fillet with the new method,compare number 9 on FIG. 2, it is possible to cut the fillet intopieces, which use the thin piece in the most valuable products so thatthe new method gives opportunity on more valuable products in theprocessing where larger a part of the fillet is sorted as the mostvaluable products than with prior art methods. Simultaneously, the area15 on the fillet is used for products so that the efficiency is betterthan in prior art methods.

FIG. 7 discloses a fish fillet 47, which is cut into a valuable neckpiece 48 and a tail piece 49 and thereafter remaining part of the filletis cut into smaller pieces (nuggets) 50 for freezing as a breadedproducts. This product is very hard to produce from fresh fish,processed by conventional methods and here a new product produced by themethod disclosed herein is provided obtaining more values from the rawmaterial as compared to conventional methods.

Form Freezing

FIG. 3 shows the principle of the form freezing. The form freezing withthe new method is based on combining blow-and touch-freezing.

A fillet 16 in FIG. 3 is placed on the conveyor belt in a freezercomprised of drop-shape aluminium beam 18 and 19 wherein these dropsgenerate a smooth surface in the upper part of the conveyor part wherethe fillet is placed on.

The side view of the aluminium beam has a drop-like shape. They havefree ends, and are rotatable around its length axis so that on the upperpart of the conveyor 18 they form a smooth surface under the fillet, buton the return way 19 they rotate such that there is an interior betweenthem where the narrower ends face downwards.

There is therefore an opening for the airflow 24 which cools thealuminium drops and therefore lowers the temperature of the aluminiumsuch that when they rotate back to the vertical position, the heat fromthe fish fillet has been removed through a touch freezing. The airflow22 from above and sidewise 23 freezes that part of the fillet, whichdoes not touch the aluminium belt so that frozen shell is generatedaround the fillet.

This method for the form freezing makes it possible to freeze a thinshell 17 in FIG. 3 round the fillet which become unfrozen within thefillet, while prior art methods for freezing take longer time to formfreeze the fish fillets where the freezing extends deeper toward thecentre of the fillet before the necessary freezing is obtained in saidshell 17 around the fillet.

Bone Removing and Removing the Fish Skin

With said form freezing the fish fillet has been form frozen so that 1-2mm shell has been generated around the fillet. This form frozen shellgives the fillet strength, which makes it possible to remove the fishskin from the fillet without removing any fish-meat simultaneously withthe fish skin, which reduces the efficiency of the processing.

FIG. 4 shows how the fish skin is being removed from the fillet 34 whereit is being advanced over rollers 35 and 36 the fish skin being pulleddown from the stiff fillet 34 so that the fish skin is removeddownwards.

It appears that the largest part of the fish bones in the bone area 6shown in FIG. 1 follows the fish skin and are removed from the fillet byremoving the fish skin, where the ends of the bones are frozen fixed tothe fish skin through the form freezing and follow the fish skin.

The roller 35 shown in FIG. 4 may be implemented as shown in FIG. 4 witha roller, which is shaped as the roller parts 28 and 29 in FIG. 4. Theyrotate around the axis 32 and the ends continually move towards and awayfrom each other so that the roller ends clamp the part of the filletwhere the bone area is located 30, so that the bones are released moreeasily from the fillet and follow the fish skin by removing it.

It is possible to remove the part of the bones, which is notautomatically removed when the skin is removed with comb 37 as shown inFIG. 5.

The comb may be shaped with two parts, which rotate around an axis 38where teeth are formed 39 so they intersect crosswise without the teethintersecting with each other. When fillet with bone area 41 faces thecomb, the comb grabs the bones and the fish-meat surrounding the bonesand the bones are pulled out of the fillet.

This may be performed mechanically and automatically, and also this maybe done manually with good success.

The comb may be formed in different ways such as by having the teethwith quadrangle shape so that, as the comb closes the tooth's intersectand if the interval between them is kept larger than the teeth, eachpart of the comb may be pulled in longitudinal direction of the axis 38towards each other so that the teeth of the comb clamp the bones betweenthem.

Manual Clamp

FIG. 8 shows how the fillet may be processed, by creating a small lobe45, simultaneously to the fish-skin removing. The lobe is cut throughthe fish skin slightly into the fish-meat around the bone area.

The fillet is subsequently form frozen as described earlier and afterthe fish skin removal, a strip with fish skin fixed to the fillet on theedge of the bone area. This fish skin strip, which is frozen to thebones, can then be removed either manually or mechanically with clampequipment as described earlier.

Skinning and Pin Bone Removal Using an Automated Device.

An automated method to remove skin and pin bones is described in FIGS.8-15. FIG. 14 is an isometric drawing of a device performing skin andbone removal from fish fillets. The side of the device 54 facing thereader has been removed in FIG. 14 to give an overview of the device. Afish fillet 51 is placed onto a conveyor belt 52 with the tail pointingin the direction of which the fillet is moving and the conveyor belt 52transports the fillet towards a guidance 53 positioning the bones in thefillet. The fillet passes sensors 55 and 56 positioning the fillet onthe conveyor belt 52. After skin and bone removal the fillet istransferred into a lane 67, which delivers the fillet for furtherprocessing.

In FIG. 9 the skin removal has started. The tail end of the fillet isconstrained in a groove on a skin-removing roller 57 and the rollerpulls the fillet so that the skin is removed from the fillet by theknife 58 and the support means 59 supports the movement of the skinalong the roller 57. For preventing the skin to separate from the roller57 a spooler shaft with ridged surface 59 is placed behind the roller 57turning in a direction opposite to the direction of the roller removingthe skin away from the fillet.

In FIGS. 10 and 11, the neck end of the fillet has passed the sensor 55and a signal is sent to the control unit of the system. FIG. 11 showsthat the carrying means 62 for the roller 57, the supporting means 61and the skin-removing knife 58 has turned approximately 45 degrees froma first position in a direction with the roller 57 into a secondposition. The bone removing knife 63 moves upwardly into the fillet andremoves the pin bones simultaneously as a the fillet is skinned andproceeds through the device.

FIGS. 12 and 13 disclose how the fillet is transported further throughthe processing line and the bone area is removed as the next filletenters the conveyor belt 52. The new fillet is first transported to theroller 57 when the bone removing knife 63 is back in resting positionand the carrying means 62 has turned back and moved the supporting means61 and the skin-removing knife 58 into first position. When the deviceis back into first position the conveyor belt 52 transports the nextfillet to the roller for skin and bone removal.

In FIG. 15 one type of knife 65 for removal of pin-bones is shown. Theknife can be formed in many ways so that it is suited for different fishtypes. Also, the knife can be formed so that the blades are on hingesand the blades can then be pulled together as the bone removal takesplace. In this manner the knife functions as the device shown in FIG. 4simultaneously cutting and removing the bones.

The invention relates therefore to processing products with a method andapparatus, which has been described here.

1. A method for processing fish or fish fillets by removing at least apart of the bone area simultaneously as the fillet is skinned, themethod comprising: form freezing the fish to be processed by combiningblow-and-touch-freezing, and removing the fish skin after the necessaryform freezing is obtained, wherein the form freezing comprises coolingthe surface of a conveyor belt by an airflow, the conveyor belt in afreezer comprising drop-shape aluminium beam, lowering the temperatureof the aluminium by airflow, such that the heat from the fish fillet isremoved through touch freezing, and wherein the airflow from above andsidewise freezes that part of the fillet, which does not touch thealuminium beam, so that frozen shell is generated around the fillet. 2.A method according to claim 1, wherein the form freezing has thefunction that the adhesion in the fish-meat adjacent to the fish skin islarger than the adhesion between the fish-meat and the fish skin whichfollows in that by removing the fish skin no-fish meat is removed withthe fish skin, and wherein the form freezing has also the function thatthe part of the bone area that is fastened to the fish skin is removedas the fish skin is removed.
 3. A method for processing fish accordingto claims 1 or 2, wherein the remaining parts of the bone area areremoved manually.
 4. A method for processing fish according to claim 1,wherein the form freezing comprises fast freezing the outmost layer ofthe product so that the freezing is not extended towards the core of thefish or the fish fillet.
 5. A method for processing fish according toclaim 1, wherein the speed of the form freezing is such that it freezes1-2 mm of the outmost layer of the fish.
 6. A method for processing fishaccording to claim 1, wherein the temperature of the outmost layer isbelow −20° C., while the core temperature of the fish-meat is largerthan 0° C.
 7. A method for processing fish according to claims 1 or 2,wherein lowering the temperature of the fish fillet in a processingincreases the value of the end product by decreasing damages due totemperature such as microorganism growth and chemical changes as aresult of changes in enzyme activity.
 8. A method for processing fishaccording to claim 1, wherein the form freezing of a fish fillet causesa lowering in the temperature during processing and increases the valueof the product due to less handling during the processing such aslooseness in the fish fillet.
 9. A method for processing fish accordingto claim 1, wherein the form freezing of the fish fillet causes alowering in the temperature during the processing.
 10. A method forprocessing fish according to claim 1, wherein the form freezingincreases the possibility of cutting the product into valuable products.11. A method for processing fish according to claim 1, wherein the formfreezing of the fish fillet results in less liquid loss in the productduring the handling and the processing.
 12. An apparatus for removing atleast a part of the bone area simultaneously as the fillet is skinned byform freezing the fish to be processed using the combiningblow-and-touch-freezing method of claim 1, the apparatus comprising:cooling means for form freezing the fish, the cooling means furthercomprising: conveyor belt, and openings for airflow 22, 23, 24 forcooling the conveyor belt and the fish fillet, device for removing skinand pin bones, the device further comprising: a conveyor belt guidancefor positioning the bones in the fillet sensors, and a skin-removingunit comprising a roller, a knife and a spooler shaft.
 13. An apparatusaccording to claim 12, wherein the upper part of the conveyor beltcomprises drop-shape aluminium beam 18 and 19 generating a smooth uppersurface.
 14. An apparatus according to claim 12, wherein the spoolershaft has a ridged surface and the spooler shaft is turning in adirection opposite to the roller for removing the skin away from thefillet.
 15. A product processed with a method and apparatus according toclaim 1.